Rhenium (Re) is a refractory metal, which exhibits unique combination of properties, making it an attractive material in a variety of applications such as catalysis, aerospace, electronics, nuclear, medical, fuel cells, etc. Albeit its high price, it has gained significant recognition as a high-performance engineering material.
Rhenium has the second highest melting point of all metals, the third highest Young's modulus of elasticity and the fourth highest density. It also has one of the highest strain hardening exponents of all elements, low coefficient of friction and high hardness, consequently having excellent wear properties. Compared with other refractory metals, it has superior tensile strength and creep-rupture strength over a wide temperature range (up to about 2000° C.). Its strength is comparable to that of carbon composites at 2500° C. These properties imply that structures made of Re have excellent mechanical stability and rigidity, enabling the design of parts with thin sections, and that this metal is extremely attractive for high-temperature structural and energy system applications. While the other refractory metals have a body centered cubic (bcc) structure, Re has a hexagonal close-packed (hcp) structure. Consequently, it does not possess a ductile-to-brittle transition and, therefore, can safely be used at subzero temperatures.